Abstract: Two ultra wideband Low Noise Amplifiers (LNAs) are presented. A common source topology is adopted for input stage to achieve wideband input matching while a cascode stage is used as the second stage to provide power gain at high frequencies. The first work is a LNA with resistive shunt feedback. It achieves a maximum power gain of 10.5 dB, a bandwidth of 10 GHz and 8.7 dB minimum noise fiqure. The power consumption is 14.28 mW from a 1.8 V supply. The second work is common source with a reuse pmos current source.